A method and reaction device for online controlling molecular weight of polyphenylene ether product

Abstract

The present invention relates to the technical field of fine chemicals, and in particular to a method and a reaction device for online control of the molecular weight of a polyphenylene ether product. The method for preparing polyphenylene ether of the present invention comprises the following steps: 1) adding oxygen and phenolic monomers to a reactor containing a solvent and a catalyst for reaction; 2) calculating the average molecular weight of the polyphenylene ether product in the reaction solution described in step 1) according to the relationship between viscosity, temperature, pressure or material concentration and the average molecular weight of the polyphenylene ether product, and when the average molecular weight of the polyphenylene ether product reaches the target molecular weight, adding a quencher to terminate the reaction, and performing post-treatment to obtain polyphenylene ether. In the production process of polyphenylene ether, the present invention monitors data such as viscosity, temperature, material concentration and pressure, calculates the molecular weight of the product in real time, and judges the reaction end point according to the calculation result, thereby realizing precise control of the reaction process and ensuring the stability of production and consistency of product quality.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemicals, in particular to a method and a reaction device for online controlling the molecular weight of a polyphenylene ether product. Background Art

[0002] Polyphenylene ether is an engineering plastic with excellent performance, which is widely used in the electronics, electrical and automotive industries. Its usual synthesis method is: using a reactor with one or more layers of stirring blades, the reactor is connected to an external pump body and a heat exchanger. Add toluene, xylene and other polyphenylene ether good solvents to the reactor, then add a composite amine formed by mixing several amines as an auxiliary catalyst and a copper salt solution as a catalyst to the solvent, and under stirring conditions, oxygen is introduced into the bottom of the reactor, and alkylphenol monomers are added through a circulation pipeline extending from the top of the reactor. Oxidative coupling reaction is carried out in the reactor to generate polyphenylene ether. During the reaction process, the circulating reaction liquid removes the reaction heat through an external heat exchanger.

[0003] The measurement technology and application of online viscometers have a history of several decades. Continuous automatic measurement and control of viscosity are required in many industrial production processes. In the petroleum industry, in the process of vacuum distillation, in the online automatic blending process of diesel, lubricating oil, fuel oil, etc., in the dewaxing and deasphalting process of petroleum, online viscosity monitoring is required to check the quality of raw materials, monitor and control production, improve product qualification rate, realize automatic blending and automatic switching of products, etc. In industries such as transportation, electricity, and glass that use heavy oil as fuel, online measurement of fuel oil viscosity can improve atomization efficiency, maintain the best combustion effect, and save fuel. In various polymerization projects, online monitoring of viscosity is used to control the reaction end point. Online monitoring of melt viscosity before chemical fiber drawing can ensure that the fiber thickness is appropriate and uniform, with less scrap rate and energy consumption. Online measurement of viscosity in the papermaking and textile industries can improve the starch conversion process and improve the quality and efficiency of gluing operations and automatic coating processes. Food, cosmetics and other industries use online viscometers to control the viscosity of intermediate processes or final products of products to achieve quality consistency of different batches of products. In addition, online viscosity measurement is also required in ink production, printing, paint spraying, detergent and cosmetic production, capsule production, and coating processes of various materials such as pouring, dipping, and rolling.

[0004] Viscosity is a quantity in fluid mechanics and an important parameter in materials science. There are many theoretical studies on it in mechanics, and more studies on the influence of viscosity on physical properties in materials science. The research and application of the two disciplines have jointly promoted the development of viscosity measurement. After Newton's law of viscosity was proposed in the 17th century, viscosity measurement had a theoretical basis. Due to the complexity of fluid mechanics, the viscosity characteristics of different fluids and at different temperatures vary greatly. To this day, the standard viscosity fluids of various countries are different. There are many methods for measuring viscosity, and the differences are also very large. Among them, the measurement principle of the vibration viscosity detector is: after the drive coil is energized, the crossbeam is excited, driving the drive shaft connected to the sensor probe to twist back and forth, and then a resonant shear wave with a fixed micro-amplitude is generated on the surface of the sensor probe. After the sensor is completely immersed in the liquid, different liquids have different viscosities, so different amplitudes of phase changes are generated between the liquid and the surface of the sensor probe. At this time, the sensor probe always maintains the same micro-amplitude resonant shear wave. If the viscosity of the medium increases, the required current will also increase accordingly. The change of fluid viscosity is reflected by the current signal which maintains the fixed amplitude of the sensor probe. The transmitter translates this changing current signal into the real viscosity value of the liquid and displays it as a numerical value.

[0005] In the prior art, the molecular weight of polyphenylene ether products is usually controlled by simply limiting the reaction temperature and time, which leads to large differences in the molecular weight of each batch of products during the production process. In subsequent modification treatments and other processes, the process conditions need to be changed frequently, which also reduces the yield of subsequent processes. Summary of the invention

[0006] In view of the shortcomings in the prior art, the present invention provides a method and a reaction device for online controlling the molecular weight of a polyphenylene ether product, which are used to solve the problems that the molecular weight control method of polyphenylene ether in the prior art mainly relies on simple temperature and time limitations, resulting in large differences in the molecular weights of various batches of products, affecting the consistency and quality of the products; due to the instability of the molecular weight of polyphenylene ether, the subsequent modification treatment section needs to frequently adjust the process conditions, which not only increases the complexity and cost of the operation, but also reduces the yield of the subsequent sections, affecting the production efficiency and economic benefits, and the like.

[0007] The first aspect of the present invention provides a method for preparing polyphenylene ether, comprising the following steps:

[0008] 1) adding oxygen and phenol monomers into a reaction kettle containing a solvent and a catalyst to react and obtain a reaction liquid;

[0009] 2) calculating the average molecular weight of the polyphenylene ether product in the reaction solution in step 1) according to the relationship between viscosity, temperature, pressure and solvent dosage and the average molecular weight of the polyphenylene ether product; when the average molecular weight of the polyphenylene ether product reaches the target molecular weight, adding a quencher to terminate the reaction, and performing post-treatment to obtain the polyphenylene ether;

[0010] The relationship between the viscosity, temperature, pressure and solvent dosage and the average molecular weight of the polyphenylene ether product satisfies the following equation:

[0011] M=5441+(a1+a2)*η b +c;

[0012] Wherein, η represents the viscosity of the polyphenylene ether reaction solution, in cP;

[0013] M represents the molecular weight of the polyphenylene ether product, in Da;

[0014] a1=-35.5+1.3e^(0.68*A); wherein A is the multiple of the mass of the solvent in step 1) relative to the mass of the phenolic monomer, and is 3-7 times;

[0015] a2=4.6e^(0.046*T); b=-0.000004*T^2 + 0.00003T + 1.076; wherein T is the temperature of the reaction solution in step 1), which is 30-70°C;

[0016] c= -83P+83; wherein P is the pressure of the reaction solution in step 1), and its value is 0.8-1.25atm.

[0017] The second aspect of the present invention provides an apparatus for online controlling the molecular weight of a polyphenylene ether product, comprising a circulating reaction device, the circulating reaction device comprising at least a reactor, a temperature and pressure sensor and a viscosity detector, the reactor comprising a first reaction liquid outlet and a reaction liquid inlet, the first reaction liquid outlet being connected to the reaction liquid inlet through a circulating pipeline; the temperature and pressure sensor and the viscosity detector are sequentially connected in series on the circulating pipeline along the outflow direction of the reaction liquid; a pump body is also provided on the circulating pipeline between the reactor and the temperature and pressure sensor; a cooling device is also provided on the circulating pipeline between the viscosity detector and the reaction liquid inlet; a nitrogen pipeline, a gas outlet, and a plurality of feed pipelines are also provided above the reactor; an oxygen pipeline and a second reaction liquid outlet are also provided below the reactor.

[0018] In some embodiments of the present invention, the plurality of feed pipelines include at least a phenol monomer feed pipeline, a catalyst and solvent feed pipeline, and a quenching agent feed pipeline.

[0019] In some embodiments of the present invention, a stirring unit is further provided in the reactor; and a heating kit is provided on the outer wall of the reactor.

[0020] In some embodiments of the present invention, a post-processing device is further included, and the post-processing device is connected to the reaction liquid outlet.

[0021] The present invention has the following beneficial effects:

[0022] 1) Precise control: By real-time monitoring and analysis of viscosity, temperature, material concentration and pressure data, the molecular weight of the product can be accurately estimated, thereby accurately determining the reaction endpoint, avoiding overreaction or incomplete reaction, and improving product consistency and quality.

[0023] 2) Reduce batch differences: Due to the use of online monitoring and automatic control systems, the molecular weight of each batch of products can be kept stable, reducing the quality differences between different batches, thereby improving the stability of the production process.

[0024] 3) Improve efficiency: Reduce the frequent adjustments of subsequent work sections caused by unstable molecular weight, improve production efficiency, and reduce scrap rate and energy consumption.

[0025] 4) Automated operation: It realizes automated control of the reaction process, reduces dependence on manual operation, and improves production safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Shown is a schematic diagram of the overall structure of the device for online controlling the molecular weight of a polyphenylene ether product disclosed in the present invention.

[0027] Figure 2 Shown is a schematic structural diagram of the viscosity detector of the present invention.

[0028] Component number description

[0029] 1 Reactor 11 Nitrogen pipeline 12 Phenolic monomer feed line 13 Catalyst and solvent inlet lines 14 Quenching agent feed line 15 Gas outlet 16 Oxygen pipeline 17 First reaction liquid outlet 18 Reaction liquid inlet 19 The second reaction liquid outlet 2 Circulation pipe 3 Pump body 4 Temperature and pressure sensor 5 Viscosity detector 51 Probe 6 Cooling device 7 Post-processing device DETAILED DESCRIPTION

[0030] Hereinafter, specific disclosed embodiments will be described in detail.

[0031] The present invention, in the production process of polyphenylene ether, accurately monitors the viscosity, temperature, material concentration and pressure data in the reaction, and calculates the molecular weight of the product in real time. Based on these calculation results, the endpoint of the reaction is accurately determined, thereby achieving accurate control of the reaction process. This method not only ensures the stability of production, but also significantly improves the consistency of product quality, and reduces the need for subsequent processing adjustments due to molecular weight fluctuations. Through online real-time monitoring and adjustment, the production cost can be effectively reduced, the process efficiency can be improved, and the economic benefits and environmental performance of the entire production process are finally improved. On this basis, the present invention is completed.

[0032] See also Figure 1-2. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change in the proportion relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0033] The first aspect of the present invention provides a method for preparing polyphenylene ether, characterized in that it comprises the following steps:

[0034] 1) adding oxygen and phenol monomers into a reaction kettle containing a solvent and a catalyst to react and obtain a reaction liquid;

[0035] 2) calculating the average molecular weight of the polyphenylene ether product in the reaction solution in step 1) according to the relationship between viscosity, temperature, pressure and solvent dosage and the average molecular weight of the polyphenylene ether product; when the average molecular weight of the polyphenylene ether product reaches the target molecular weight, adding a quencher to terminate the reaction, and performing post-treatment to obtain the polyphenylene ether;

[0036] The relationship between the viscosity, temperature, pressure and solvent dosage and the average molecular weight of the polyphenylene ether product described in the present invention is based on the Mark-Houwink equation: [η] = KM a , that is, lg[η]=lgK+a*lgM, where K and a are constants. [η] is the intrinsic viscosity of the polymer, and its physical meaning is the specific viscosity when the concentration of the polymer solution approaches zero. The contribution of the polymer to the viscosity in the polymer solution is not simply linearly related to its molecular weight, but a power function related to temperature.

[0037] The reaction liquid is regarded as a uniform viscous substance, and the polyphenylene ether reaction liquid viscosity η is used to replace the polyphenylene ether intrinsic viscosity [η] in the formula. The viscosity-molecular weight conversion formula used in the present invention is:

[0038] M=5441+(a1+a2)*η b +c+d;

[0039] Wherein, η represents the viscosity of the polyphenylene ether reaction solution, and the unit is cP (centipoise);

[0040] M represents the molecular weight of the polyphenylene ether product, in Da (Dalton);

[0041] a1=-35.5+1.3e^(0.68*A); wherein A is the multiple of the mass of the solvent in step 1) relative to the mass of the phenolic monomer, and is 3-7 times;

[0042] a2=4.6e^(0.046*T); b=-0.000004*T^2 + 0.00003T + 1.076; wherein T is the temperature of the reaction solution in step 1), which is 30-70°C;

[0043] c= -83P+83; wherein P is the pressure of the reaction solution in step 1), and its value is 0.8-1.25atm.

[0044] a1 According to step 1), the mass ratio of the solvent to the phenolic monomer is (3-7):1, which can be (3-3.5):1, (3.5-4):1, (4-4.5):1, (4.5-5):1, (5-5.5):1, (5.5-6):1, (6-6.5):1 or (6.5-7):1, etc. The value range is -25.5-116.3, which can be -25.5--21.5, -21.5--15.8, -15.8--7.8, -7.8-3.5, 3.5-19.2, 19.2-41.4, 41.4-72.5 or 72.5-116.3, etc.

[0045] a2 According to step 1), the temperature of the reaction solution is 30-70°C, which can be 30-35°C, 35-40°C, 40-45°C, 45-50°C, 50-55°C, 55-60°C, 60-65°C or 65-70°C, etc., and the value range is 18.3-115.1, which can be 18.3-23, 23-29, 29-36.5, 36.5-45.9, 45.9-57.7, 57.7-72.7, 72.7-91.5 or 91.5-115.1, etc.

[0046] b According to step 1), the temperature of the reaction solution is 30-70°C, which can be 30-35°C, 35-40°C, 40-45°C, 45-50°C, 50-55°C, 55-60°C, 60-65°C or 65-70°C, etc., and the value range is 1.059-1.073, which can be 1.059-1.061, 1.061-1.063, 1.063-1.066, 1.066-1.068, 1.068-1.069, 1.069-1.071, 1.071-1.072 or 1.072-1.073, etc.

[0047] c According to step 1), the pressure of the reaction liquid is 0.8-1.25 atm, which can be 0.8-0.95 atm, 0.95-1 atm, 1-1.1 atm or 1.1-1.25 atm, etc., and the value range is -21-17, which can be -21--8, -8-0, 0-4 or 4-17, etc.

[0048] d=0, then the equation is: M=5441+(a1+a2)*η b +c; where a1, a2, b, and c have the same values ​​as before.

[0049] a1, a2, b, c, d are dimensionless constants. Specifically: a1 is related to the mass ratio of the solvent to the phenolic monomer. When toluene is used as the solvent and dimethylphenol is used as the phenolic monomer, the relationship between the value of a1 and the amount of toluene is shown in Table 1.

[0050] Table 1

[0051]

[0052] Among them, a2 and b are related to the reaction liquid temperature. The relationship between the values ​​of a2 and b and the reaction liquid temperature at 30-70°C is shown in Table 2. When the value of a1+a2 is lower than 30 or greater than 120, the error of the calculated molecular weight increases significantly. The former error comes from the change of rheological properties of high viscosity solutions, and the latter comes from the systematic error of the viscosity detector for low concentration substances.

[0053] Table 2

[0054]

[0055] Among them, c is a pressure correction term based on normal pressure, which has a small influence. The relationship between the value of c and the pressure of the reaction liquid is shown in Table 3.

[0056] Table 3

[0057]

[0058] Among them, d is other correction items mainly caused by vibration, which are mainly affected by the vibration of the branch pump body. Depending on the operating state of the reaction device, the value of d is different, ranging from -50 to 50. The difference between the molecular weight measured by the device control and the molecular weight actually detected by the product is brought into different d values ​​to correct the formula. The existing constant items such as vibration have been included in the value of the formula coefficient 5441, so under the premise that the reaction stirring device and the branch pump body remain unchanged, the d value is 0.

[0059] The above formula is applicable to polyphenylene ether with a molecular weight of 8000-40000 Da, which can be 8000-10000 Da, 10000-12000 Da, 12000-15000 Da, 15000-18000 Da, 18000-20000 Da, 20000-25000 Da, 25000-30000 Da, 30000-35000 Da or 35000-40000 Da, etc. The viscosity of the polyphenylene ether solution is 20-500 cP, which can be 20-50 cP, 50-100 cP, 100-150 cP, 150-200 cP, 200-250 cP, 250-300 cP, 300-350 cP, 350-400 cP, 400-450 cP, etc. cP or 450-500 cP.

[0060] In the method for preparing polyphenylene ether provided by the present invention, the average molecular weight is the number average molecular weight (Mn),

[0061] The calculation formula of number average molecular weight (Mn) is as follows:

[0062]

[0063] Where Ni represents the number of the i-th polymer chain; Mi represents the molecular weight of the i-th polymer chain.

[0064] In the method for preparing polyphenylene ether provided by the present invention, the concentration of oxygen in step 1) is 21-100%, preferably 90-10%. The addition rate of oxygen and phenolic monomer, that is, the molar ratio of oxygen added to phenolic monomer per unit time is (0.6-1.5):1, which can be (0.6-0.8):1, (0.8-1.0):1 or (1.0-1.5):1, preferably (0.8-1.0):1.

[0065] In the method for preparing polyphenylene ether provided by the present invention, the phenolic monomer in step 1) is selected from one or more of 2,6-dimethylphenol, 2,6-diethylphenol, 2-ethyl-6-n-propylphenol, 2-ethyl-6-bromophenol or 2-methyl-6-n-butylphenol, preferably 2,6-dimethylphenol, and the phenolic monomer is added in two parts, the monomer pre-added to the reaction accounts for 10-15% of the total monomer amount, which can be 10-12% or 12-15%, preferably 12%; the remaining monomers are uniformly added dropwise within 50-70 minutes, which can be 50-60 minutes or 60-70 minutes. By adding the reaction raw material phenolic monomers in batches, the concentration of phenolic monomers in the reaction system is maintained at a relatively low concentration, the mutual reaction between phenolic monomers is reduced, the generation of low molecular weight polyphenylene ether is reduced, and the product polyphenylene ether is helpful to form a higher molecular weight polymer.

[0066] In the method for preparing polyphenylene ether provided by the present invention, the solvent in step 1) is a substance that can dissolve phenolic monomers and catalysts, including aromatic hydrocarbons and / or halogenated hydrocarbons, and can be selected from one or more of benzene, toluene, ethylbenzene, xylene, chloroform, dichloroethane, trichloroethane or chlorobenzene, preferably toluene. The mass ratio of the solvent to the phenolic monomer is (3-7):1, and can be selected from (3-3.5):1, (3.5-4):1, (4-4.5):1, (4.5-5):1, (5-5.5):1, (5.5-6):1, (6-6.5):1 or (6.5-7):1, etc., preferably 5:1. This mass ratio range helps to maintain the viscosity of the reaction system within a range suitable for monitoring.

[0067] In the method for preparing polyphenylene ether provided by the present invention, the reaction temperature in step 1) is 30-70°C, which can be 30-35°C, 35-40°C, 40-45°C, 45-50°C, 50-55°C, 55-60°C, 60-65°C or 65-70°C, etc., and is preferably 50°C; the reaction pressure condition is 0.8-1.25atm, which can be 0.8-0.95 atm, 0.95-1 atm, 1-1.1 atm or 1.1-1.25 atm, etc., and is preferably carried out under normal pressure.

[0068] In the method for preparing polyphenylene ether provided by the present invention, the catalyst in step 1) is divided into a copper-based main catalyst and an auxiliary catalyst, the copper-based main catalyst is selected from one or more of cuprous compounds, copper compounds or copper salts, and the auxiliary catalyst is selected from one or more of secondary alkylene diamines, tertiary amines or secondary amines.

[0069] In the method for preparing polyphenylene ether provided by the present invention, the copper-based main catalyst described in step 1) is selected from one or more of cuprous chloride, cuprous bromide, cuprous nitrate, cuprous sulfate, cupric chloride, cupric bromide, cupric nitrate, cupric sulfate or a copper salt obtained by reacting cupric oxide, cuprous oxide and hydrohalic acid; preferably one or more of cuprous chloride, cuprous bromide, cupric chloride or cupric bromide.

[0070] In the method for preparing polyphenylene ether provided by the present invention, the auxiliary catalyst described in step 1) is selected from one or more of N,N-di-tert-butylethylenediamine, N,N-diisopropylethylenediamine, trimethylamine, triethylamine, tripropylamine, tributylamine, diethylmethylamine, dimethylpropylamine, dimethyl-n-butylamine, dimethylamine, diethylamine, piperazine, morpholine or methylmorpholine.

[0071] In the method for preparing polyphenylene ether provided by the present invention, the molar ratio of the copper-based main catalyst to the phenolic monomer in step 1) is (0.001-0.3):1, which can be (0.001-0.05):1, (0.05-1):1, (1-2):1 or (2-3):1, etc.

[0072] In the method for preparing polyphenylene ether provided by the present invention, when the auxiliary catalyst described in step 1) is a secondary alkylene diamine, the molar ratio of the auxiliary catalyst to the copper salt is (0-4):1, which can be selected from (0-1):1, (1-2):1 (2-3):1 or (3-4):1, etc.; when the auxiliary catalyst is a tertiary amine, the molar ratio of the auxiliary catalyst to the copper salt is (2-60):1, which can be selected from (2-15):1, (15-30):1, (30-45):1 or (45-60):1, etc.; when the auxiliary catalyst is a secondary amine, the molar ratio of the auxiliary catalyst to the copper salt is (0-5):1, which can be selected from (0-1):1, (1-2):1 (2-3):1, (3-4):1 or (4-5):1, etc.

[0073] In the method for preparing polyphenylene ether provided by the present invention, the target molecular weight in step 2) is 8000-40000 Da, which can be 8000-10000 Da, 10000-12000 Da, 12000-15000 Da, 15000-18000 Da, 18000-20000 Da, 20000-25000 Da, 25000-30000 Da, 30000-35000 Da or 35000-40000 Da, etc.; when the average molecular weight of the polyphenylene ether product reaches the target molecular weight, the viscosity of the reaction solution in step 1) is 20-500 cP, which can be 20-50 cP, 50-100 cP, 100-150 cP, 150-200 cP, 200-250 cP, 250-300 cP, 300-350 cP, etc. cP, 350-400cP, 400-450 cP or 450-500 cP.

[0074] In the method for preparing polyphenylene ether provided by the present invention, the quencher in step 2) is a strong chelate ligand, preferably EDTA.

[0075] In the method for preparing polyphenylene ether provided by the present invention, the amount of the quencher in step 2) is 1-5 times the copper ion equivalent in the copper-based main catalyst in step 1), which can be 1-2 times, 2-3 times, 3-4 times or 4-5 times, preferably 2 times.

[0076] In the method for preparing polyphenylene ether provided by the present invention, the time for stopping the reaction in step 2) is 10-60 min, which can be 10-15 min, 15-30 min, 30-45 min or 45-60 min, etc., and is preferably 15 min.

[0077] In the method for preparing polyphenylene ether provided by the present invention, the post-treatment in step 2) includes impurity removal, precipitation, washing and drying.

[0078] The second aspect of the present invention provides an apparatus for online controlling the molecular weight of a polyphenylene ether product, comprising a circulating reaction device, the circulating reaction device comprising at least a reactor 1, a temperature and pressure sensor 4 and a viscosity detector 5, the reactor 1 comprising a first reaction liquid outlet 17 and a reaction liquid inlet 18, the first reaction liquid outlet 17 being connected to the reaction liquid inlet 18 via a circulating pipe 2; the temperature and pressure sensor 4 and the viscosity detector 5 are sequentially connected in series on the circulating pipe 2 along the outflow direction of the reaction liquid; a pump body 3 is also provided on the circulating pipe 2 between the reactor 1 and the temperature and pressure sensor 4; a cooling device 6 is also provided on the circulating pipe 2 between the viscosity detector 5 and the reaction liquid inlet 18; a nitrogen pipeline 11, a gas outlet 15, and a plurality of feed pipelines are also provided above the reactor 1; an oxygen pipeline 16 and a second reaction liquid outlet 19 are also provided below the reactor 1.

[0079] In some embodiments of the present invention, a pump body 3 is first arranged along the outflow direction of the reaction liquid, which helps to maintain the pressure stability in the circulation pipeline 2, and uses the filtering device provided by the pump body 3 to prevent foreign matter from entering the subsequent device; then, a temperature and pressure sensor 4 is arranged after the pump body 3, and by measuring the temperature and pressure at the same point, the error is reduced to ensure the data consistency with the subsequent viscosity detector; a viscosity detector 5 is arranged after the temperature and pressure sensor, and this design is to ensure the consistency of temperature, pressure and viscosity data, which helps to accurately monitor the reaction situation; finally, a cooling device 6 is arranged after the viscosity detector 5. Placing the cooling device 6 here can avoid the problem of uneven temperature distribution of the material after cooling, better remove the reaction heat, and prevent large fluctuations in the measured temperature and viscosity.

[0080] In some embodiments of the present invention, the external circulation mode of the circulation pipeline 2 not only allows the reaction liquid to flow into the viscosity detector 5, but also serves to remove the reaction heat and enhance stirring.

[0081] In some embodiments of the present invention, the plurality of feed pipelines at least include a phenolic monomer feed pipeline 12 , a catalyst and solvent feed pipeline 13 , and a quenching agent feed pipeline 14 .

[0082] In some embodiments of the present invention, a stirring unit is further provided in the reactor 1; and a heating kit is provided on the outer wall of the reactor 1.

[0083] In some embodiments of the present invention, a post-processing device 7 is further included, and the post-processing device 7 is connected to the reaction liquid outlet 19 .

[0084] In some embodiments of the present invention, the temperature and pressure sensor 4 is a SI-706 pressure and temperature sensor.

[0085] In some embodiments of the present invention, the viscosity detector 5 is a vibration viscosity detector or a stirring viscosity detector.

[0086] In some embodiments of the present invention, the viscosity detector 5 is an XL7 online viscometer sold by Hydramotion, which is a vibration viscosity detector.

[0087] The use process of the present invention:

[0088] 1) Carry out the reaction in reactor 1. After nitrogen replacement of reactor 1, make the oxygen content below 2%, and add solvent. Start the stirring and external circulation of reactor 1, add catalyst and solvent, start the cooling device of reactor 1, reduce the temperature in the reactor to below 30°C, and inject nitrogen through the nitrogen pipeline 11 on the upper part of reactor 1, so that the oxygen content in the upper space of reactor 1 is always less than 10%. Inject part of the monomer into reactor 1 from the phenol monomer feed pipeline 12, and the remaining reaction monomer is added at a uniform rate during the reaction. At the same time, oxygen is introduced into the reactor from the oxygen pipeline 16 at the bottom of reactor 1. From the start of the reaction to the completion of the addition of the reaction monomer, gradually increase the temperature from 30°C to the reaction temperature, and maintain it until the end of the reaction;

[0089] 2) The viscosity detector monitors the viscosity of the reaction liquid in real time. The values ​​of a1, a2, b, c and d in the formula are determined according to the conditions used in the reaction. The molecular weight of the polyphenylene ether material in the kettle is calculated in real time according to the viscosity and conversion formula. When the molecular weight reaches 80% of the target molecular weight, the power of the stirring unit in the reactor 1 is gradually increased. When the average molecular weight of the polyphenylene ether product in the reaction liquid monitored in real time reaches the target molecular weight, the oxygen pipeline 16 is closed and a quenching agent is added. After stirring, the material is discharged into the post-processing device 7, and a granular polyphenylene ether product is obtained through subsequent processing steps such as impurity removal, precipitation, washing, and drying.

[0090] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below in conjunction with embodiments and drawings.

[0091] In the following examples, unless otherwise specified, all reaction raw materials are commercially available products.

[0092] Unless otherwise specified, the purity of each product in each embodiment of the present invention exceeds 98%. Example 1

[0093] Accurately produce polyphenylene ether with different molecular weights up to 10000Da

[0094] The 100-liter reactor was replaced with nitrogen until the oxygen content was less than 2%, and then 45.1 kg of toluene was added. The stirring and external circulation of the reactor were turned on, and the circulation volume of the external circulation was 1000 liters / hour. The external circulation pumped the material in the reactor into the viscosity monitoring device, and the reaction liquid returned to the reactor along the pipeline after real-time measurement of the material viscosity.

[0095] Prepare the catalyst: 200 g methanol, 52.9 g cuprous bromide (0.37 mol), 13 g N,N-di-tert-butylethylenediamine (0.076 mol), 75 g dimethylbutylamine (0.74 mol), 32 g morpholine (0.37 mol), mix and stir until completely dissolved, then add to the kettle.

[0096] The temperature in the reactor was adjusted to 30°C through the reactor temperature control device. Then, a total of 9.02 kg of the polymerization monomer 2,6-dimethylphenol was released, 1.08 kg was released into the reactor, and the remaining 7.94 kg of monomer was uniformly added to the reactor in 60 minutes; at the same time as the monomer was added, oxygen was introduced from the bottom of the reactor at a flow rate of 25 liters / minute. At the same time, the reaction temperature was slowly and uniformly increased from 30°C to 50°C in 60 minutes through the temperature control device and the temperature was kept unchanged. During the reaction, nitrogen was continuously introduced at a rate of 300 liters / minute above the reactor to control the oxygen concentration in the gas phase space in the reactor below 10%.

[0097] According to the reaction conditions, enter the appropriate parameters into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=3.5; a2=45.9; b=1.068; c=0; d=0, the formula is: M=5441+49.3*η 1.068 .

[0098] The viscosity of the reaction liquid is monitored in real time by a viscosity detector, and the molecular weight of the polyphenylene ether material in the kettle is calculated in real time according to the viscosity and the conversion formula. When the molecular weight reaches 80% of the target molecular weight, the stirrer power is gradually increased. When the molecular weight detected in real time reaches the target molecular weight, the oxygen inlet is closed and 40g of quencher is added. The timing starts after the addition of the reaction monomer is completed, and it takes a total of 32 minutes. After stirring for 15 minutes, the material is discharged into the subsequent processing device. After the steps of impurity removal, precipitation, washing, drying, etc., a granular polyphenylene ether product is obtained.

[0099] The intrinsic viscosity of the polymer was measured using an Ubbelohde viscometer according to the method in GBT1632-1993, and the molecular weight and molecular weight distribution of the polymer were calculated, as shown in Table 1. The specific conditions were as follows: 1.25 g of the polymer was dissolved in 100 g of chloroform, and the solution was diluted to a constant volume to prepare solutions of different concentrations, and an Ubbelohde suspension viscometer was used, with a constant temperature water bath temperature of 25°C.

[0100] Embodiment 2-10

[0101] Accurately produce polyphenylene ether with different molecular weights

[0102] Compared with Example 1, the same feeding parameters were used, and the molecular weight of the product was controlled by extending the reaction time. The same viscosity-molecular weight calculation formula as in Example 1 was used to monitor the reaction progress and determine the reaction stop time through the online viscosity data of the reaction solution. At the same time, the timing was started after all the reaction monomers were added and the temperature of the reactor was raised to 50°C, and the reaction time of the insulation stage of each batch of reactions was recorded. The molecular weight and molecular weight distribution of the polymer were calculated for each batch of polyphenylene ether products according to the method in GBT1632-1993, as shown in Table 4.

[0103] Table 4 Reaction conditions and product data of Examples 1-10

[0104]

[0105] The above-mentioned Examples 2-10 demonstrate that the production method of the present invention is applicable to the production of polyphenylene ethers of various molecular weights, while being able to maintain a good molecular weight control effect. Embodiment 11

[0106] Except that the amount of solvent toluene was changed to 63.14 kg and the constant temperature in the reactor during the reaction was controlled to 30°C, the same catalyst solution as in Example 1 was prepared, the same raw materials as in Example 1 were added, and the reaction was carried out in the same manner as in Example 1. According to the changes in the conditions selected for the reaction, appropriate parameters were introduced into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=116.3; a2=18.3; b=1.073; c=0; d=0, and the formula is: M=5441+134.6*η 1.073 .

[0107] As in Example 1, when the molecular weight reaches 80% of the target molecular weight, the stirrer power is gradually increased. When the real-time detected molecular weight reaches the target molecular weight, the reaction is stopped and a quencher is added, and a granular polyphenylene ether product is obtained through the steps of impurity removal, precipitation, washing, drying, etc. The reaction takes a total of 75 minutes. Example 12

[0108] Except that the amount of solvent toluene was changed to 58.63 kg and the constant temperature in the reactor during the reaction was controlled to 35°C, the same catalyst solution as in Example 1 was prepared, the same raw materials as in Example 1 were added, and the reaction was carried out in the same manner as in Example 1. According to the changes in the conditions selected for the reaction, appropriate parameters were introduced into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=72.5; a2=23.0; b=1.072; c=0; d=0, and the formula is: M=5441+95.5*η 1.072 .

[0109] As in Example 1, when the molecular weight reaches 80% of the target molecular weight, the stirrer power is gradually increased. When the real-time detected molecular weight reaches the target molecular weight, the reaction is stopped and a quencher is added, and a granular polyphenylene ether product is obtained through the steps of impurity removal, precipitation, washing, drying, etc. The reaction takes a total of 62 minutes. Embodiment 13

[0110] Except that the amount of solvent toluene was changed to 54.12 kg and the constant temperature in the reactor during the reaction was controlled to 40°C, the same catalyst solution as in Example 1 was prepared, the same raw materials as in Example 1 were added, and the reaction was carried out in the same manner as in Example 1. According to the changes in the conditions selected for the reaction, appropriate parameters were introduced into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=41.4; a2=29.0; b=1.071; c=0; d=0, the formula is: M=5441+70.4*η 1.071 .

[0111] As in Example 1, when the molecular weight reaches 80% of the target molecular weight, the power of the stirrer is gradually increased. When the real-time detected molecular weight reaches the target molecular weight, the reaction is stopped and a quencher is added, and a granular polyphenylene ether product is obtained through the steps of impurity removal, precipitation, washing, drying, etc. The reaction takes a total of 55 minutes. Embodiment 14

[0112] Except that the amount of solvent toluene was changed to 49.61 kg and the constant temperature in the reactor during the reaction was controlled to 45°C, the same catalyst solution as in Example 1 was prepared, the same raw materials as in Example 1 were added, and the reaction was carried out in the same manner as in Example 1. According to the changes in the conditions selected for the reaction, appropriate parameters were introduced into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=19.2; a2=36.5; b=1.069; c=0; d=0, and the formula is: M=5441+55.7*η 1.069 .

[0113] As in Example 1, when the molecular weight reaches 80% of the target molecular weight, the power of the stirrer is gradually increased. When the molecular weight detected in real time reaches the target molecular weight, the reaction is stopped and a quencher is added, and a granular polyphenylene ether product is obtained through the steps of impurity removal, precipitation, washing, drying, etc. The reaction takes a total of 36 minutes. Embodiment 15

[0114] Except that the amount of solvent toluene was changed to 40.59 kg and the constant temperature in the reactor during the reaction was controlled to 55°C, the same catalyst solution as in Example 1 was prepared, the same raw materials as in Example 1 were added, and the reaction was carried out in the same manner as in Example 1. According to the changes in the conditions selected for the reaction, appropriate parameters were introduced into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=-7.8; a2=57.7; b=1.066; c=0; d=0, and the formula is: M=5441+50.0*η 1.066 .

[0115] As in Example 1, when the molecular weight reaches 80% of the target molecular weight, the power of the stirrer is gradually increased. When the molecular weight detected in real time reaches the target molecular weight, the reaction is stopped and a quencher is added, and a granular polyphenylene ether product is obtained through the steps of impurity removal, precipitation, washing, drying, etc. The reaction takes a total of 32 minutes. Example 16

[0116] Except that the amount of solvent toluene was changed to 36.08 kg and the constant temperature in the reactor during the reaction was controlled to 60°C, the same catalyst solution as in Example 1 was prepared, the same raw materials as in Example 1 were added, and the reaction was carried out in the same manner as in Example 1. According to the changes in the conditions selected for the reaction, appropriate parameters were introduced into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=-15.8; a2=72.7; b=1.064; c=0; d=0, and the formula is: M=5441+56.9*η 1.064 .

[0117] As in Example 1, when the molecular weight reaches 80% of the target molecular weight, the stirrer power is gradually increased. When the real-time detected molecular weight reaches the target molecular weight, the reaction is stopped and a quencher is added, and a granular polyphenylene ether product is obtained through the steps of impurity removal, precipitation, washing, drying, etc. The reaction takes a total of 23 minutes. Embodiment 17

[0118] Except that the amount of solvent toluene was changed to 31.57 kg and the constant temperature in the reactor during the reaction was controlled to 65°C, the same catalyst solution as in Example 1 was prepared, the same raw materials as in Example 1 were added, and the reaction was carried out in the same manner as in Example 1. According to the changes in the conditions selected for the reaction, appropriate parameters were introduced into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=-21.5; a2=91.5; b=1.061; c=0; d=0, and the formula is: M=5441+70.0*η 1.061 .

[0119] As in Example 1, when the molecular weight reaches 80% of the target molecular weight, the stirrer power is gradually increased. When the real-time detected molecular weight reaches the target molecular weight, the reaction is stopped and a quencher is added, and a granular polyphenylene ether product is obtained through the steps of impurity removal, precipitation, washing, drying, etc. The reaction takes a total of 17 minutes. Embodiment 18

[0120] Except that the amount of solvent toluene was changed to 27.06 kg and the constant temperature in the reactor during the reaction was controlled to 70°C, the same catalyst solution as in Example 1 was prepared, the same raw materials as in Example 1 were added, and the reaction was carried out in the same manner as in Example 1. According to the changes in the conditions selected for the reaction, appropriate parameters were introduced into the viscosity-molecular weight calculation formula M=5441+(a1+a2)*η b +c+d, where a1=-25.5; a2=115.1; b=1.059; c=0; d=0, and the formula is: M=5441+89.6*η 1.059 .

[0121] As in Example 1, when the molecular weight reaches 80% of the target molecular weight, the stirrer power is gradually increased. When the real-time detected molecular weight reaches the target molecular weight, the reaction is stopped and a quencher is added, and a granular polyphenylene ether product is obtained through the steps of impurity removal, precipitation, washing, drying, etc. The reaction takes a total of 12 minutes.

[0122] Table 5 Reaction conditions and product data of Examples 11-18

[0123]

[0124] Embodiment 19

[0125] Parallel experiments on polyphenylene ether under the same conditions

[0126] Compared with Example 1, the same feeding parameters are maintained, and the same viscosity-molecular weight calculation formula as in Example 1 is used to monitor the reaction progress and determine the reaction stop time. The timing starts after all the reaction monomers are added and the temperature of the reactor rises to 50°C, and the reaction time of the insulation stage of the reaction is recorded. The prepared reaction solution is introduced into the subsequent process section, and after the steps of impurity removal, precipitation, washing, drying, etc., a granular polyphenylene ether product is obtained. Repeat the above production scheme to obtain 4 batches of polyphenylene ether products. The molecular weight and molecular weight distribution of the polymer are calculated for each batch of polyphenylene ether products according to the method in GBT1632-1993, as shown in Table 6.

[0127] Table 6 Example 19 Product Data

[0128]

[0129] From the data in Table 6, it can be seen that the molecular weight difference between each batch of polyphenylene ether products prepared by the polyphenylene ether method of the present invention is relatively small.

[0130] Comparative Example 1

[0131] Parallel experiment of polyphenylene ether without viscosity control under the same conditions

[0132] Compared with Example 1, the same feeding parameters are used. The timing starts after all the reaction monomers are added and the temperature of the reactor is raised to 50°C. After the timing reaction lasts for 32 minutes, the oxygen is immediately turned off and the quencher is added. After stirring for 15 minutes, the reaction liquid is introduced into the subsequent process section. The prepared reaction liquid is introduced into the subsequent process section, and after the steps of impurity removal, precipitation, washing, drying, etc., a granular polyphenylene ether product is obtained.

[0133] The above production scheme was repeated to obtain 5 batches of polyphenylene ether products. The molecular weight and molecular weight distribution of the polymer were calculated for each batch of polyphenylene ether products according to the method in GBT1632-1993, as shown in Table 7.

[0134] Table 7 Product data of Comparative Example 1

[0135]

[0136] From the data in Table 7, it can be seen that the molecular weights of the polyphenylene ether products prepared by the traditional polyphenylene ether method vary greatly from batch to batch.

[0137] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

[0138] The applicant declares that the present invention is explained by the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0139] The above embodiments are preferred cases of the present invention and are not intended to limit the protection scope of the present invention. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present invention.

[0140] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for preparing polyphenylene ether, characterized in that: The steps include: 1) adding oxygen and phenolic monomers into a reaction kettle containing a solvent and a catalyst to react and obtain a reaction liquid; 2) calculating the average molecular weight of the polyphenylene ether product in the reaction solution in step 1) according to the relationship between viscosity, temperature, pressure and solvent dosage and the average molecular weight of the polyphenylene ether product; when the average molecular weight of the polyphenylene ether product reaches the target molecular weight, adding a quencher to terminate the reaction, and performing post-treatment to obtain the polyphenylene ether; The relationship between the viscosity, temperature, pressure and solvent dosage and the average molecular weight of the polyphenylene ether product satisfies the following equation: M=5441+(a1+a2)*η b +c; Wherein, η represents the viscosity of the polyphenylene ether reaction solution, in cP; M represents the molecular weight of the polyphenylene ether product, in Da; a1=-35.5+1.3e^(0.68*A); wherein A is the multiple of the mass of the solvent in step 1) relative to the mass of the phenolic monomer, and is 3-7 times; a2=4.6e^(0.046*T); b=-0.000004*T^2+0.00003T+1.076; wherein T is the temperature of the reaction solution in step 1), which is 30-70°C; c=-83P+83; wherein P is the pressure of the reaction liquid in step 1), and its value is 0.8-1.25atm.

2. The method for preparing polyphenylene ether according to claim 1, characterized in that: Includes any one or more of the following features: A1) The concentration of oxygen in step 1) is 21-100%; A2) the phenolic monomer in step 1) is selected from one or more of 2,6-dimethylphenol, 2,6-diethylphenol, 2-ethyl-6-n-propylphenol, 2-ethyl-6-bromophenol or 2-methyl-6-n-butylphenol; A3) in step 1), the addition rate ratio of the oxygen to the phenolic monomer is (0.6-1.5):1; A4) the solvent in step 1) is an aromatic hydrocarbon and / or a halogenated hydrocarbon; A5) the mass ratio of the solvent to the phenolic monomer in step 1) is (3-7):1; A6) the reaction temperature of step 1) is 30-70°C; A7) The pressure condition of the reaction in step 1) is 0.8-1.25 atm; A8) the catalyst in step 1) is divided into a copper-based main catalyst and an auxiliary catalyst; A9) the amount of the solvent used in step 2) is 3-7 times the mass of the phenolic monomer; A10) the target molecular weight of step 2) is 8000-40000Da; A11) when the average molecular weight of the polyphenylene ether product in step 2) reaches the target molecular weight, the viscosity of the reaction solution in step 1) is 20-500 c P; A12) the quencher in step 2) is a strong chelate ligand; A13) The time for stopping the reaction in step 2) is 10-60 min; A14) The post-treatment described in step 2) includes impurity removal, precipitation, washing and drying.

3. The method for preparing polyphenylene ether according to claim 2, characterized in that: Includes any one or more of the following features: A41) the solvent in step 1) is selected from one or more of benzene, toluene, ethylbenzene, xylene, chloroform, dichloroethane, trichloroethane or chlorobenzene; A81) the copper-based main catalyst in step 1) is selected from one or more of cuprous compounds, cupric compounds or cupric salts; A82) the auxiliary catalyst in step 1) is selected from one or more of secondary alkylene diamines, tertiary amines or secondary amines; A83) In step 1), the molar ratio of the copper-based main catalyst to the phenolic monomer is (0.001-0.3):1; A84) The amount of the quenching agent in step 1) is 1-5 times the copper ion equivalent in the copper-based main catalyst; A121) The quenching agent described in step 2) is EDTA.

4. The method for preparing polyphenylene ether according to claim 3, characterized in that: Includes any one or more of the following features: A811) The copper-based main catalyst in step 1) is selected from one or more of cuprous chloride, cuprous bromide, cuprous nitrate, cuprous sulfate, cupric chloride, cupric bromide, cupric nitrate, cupric sulfate, or a copper salt obtained by reacting cupric oxide, cuprous oxide and a hydrohalic acid; A821) the auxiliary catalyst in step 1) is selected from one or more of N,N-di-tert-butylethylenediamine, N,N-diisopropylethylenediamine, trimethylamine, triethylamine, tripropylamine, tributylamine, diethylmethylamine, dimethylpropylamine, dimethyl-n-butylamine, dimethylamine, diethylamine, piperazine, morpholine or methylmorpholine; A822) When the auxiliary catalyst in step 1) is a secondary alkylene diamine, the molar ratio of the auxiliary catalyst to the copper salt in step A81) is (0-4):1; A823) When the auxiliary catalyst in step 1) is a tertiary amine, the molar ratio of the auxiliary catalyst to the copper salt in step A81) is (2-60):1; A824) When the auxiliary catalyst described in step 1) is a secondary amine, the molar ratio of the auxiliary catalyst to the copper salt described in A81) is (0-5):1.

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